Binder for the manufacture of refractory conductors.



UNITED srnrns Parana ora ion.

WILLIAM B.

ooonrncn. or SGHENEC'I'ADY, NEW YORK, assroivoa r GENERAL nnno'rarc company, A CORPORATION on NEW "roan.

BINDER FOR THE MANUFACTURE OF REFRACTORY-CONDUCTOR.

No Drawing.

. Patented May 1a, 1912.

To. all whom it may concern:

. Be it known that I, WILLIAM D. Coomnen,

a citizen of the United States, residing at Schenectady, count of Schenectady, State 5 of New York, have invented certain new and useful Improvements in Binders for the Manufacture of Refractory Conductors, of

which the following is a specification.

This invention relates to the production of refractory electrical conductors suitable for use in incandescent lamps, electrical furnaces, and other apparatus.

My invention comprises a process whereby refractory material, even t ough non-ductile, may be shaped into wires, plates; rods, or other forms, and then consolidated into a coherent conductor ca able of converting electrical energy into ight at enormously high temperatures.

According to my invention, a refractory element, alloy, compound or mixture is incorporated in a metallic binder, and the product so obtained is squirted or otherwise shaped into rods or filaments and then treated to drive out the easily vaporizable material of the binder and to consolidate and sintcr together the refractory residue.

My process is applicable to a great variety of refractory metals and materials, such, for instance, as tungsten, molybdenum, boron, zirconium, tantalum, titanium, graphite, or compounds of alloys of any of these, or of other materials of the same general refractor nature. I 35 is a binding material I use an alloy containing cadmium, lead and mercury. The

alloy may have the following proportions,

cadmium 42 parts, mercury -53 parts, lead 5 parts. This binder does not appear to 40 chemically combine with the refractory material with which it is impregnated, and consequently the process of manufacture is a plicable to all the materials above mentioned and to many others.

In eneral, the binding material serves to give t e body ductility and strength, and in some cases to increase its electrical conductivity. It is retained in the mixture only until the body has been worked or formed 50 into the desired shape." It is then driven out by heat treatment and leaves .behind a refractory coherent wire or rod suitable for use in lamps.

In order that my invention may be easily 55 practised, I have hereinafter described the processes applied to the metal tungsten, but thls spec fic application is to be regarded as only typlcal and as showing but one of numerous applications.

Tungsten suitable for use according to my process ma be made by reduction of tungsten trloxi with hydrogen according to the general process well known to chemists. This reaction should be carefully conducted so that the tungsten powder Wlll be finely divided and of a high degree of purity.

To compound the binder for use with tungsten or other refractory powder, I melt together the cadmium and lead and then add the mercury. I find that the alloy thus produced is homogeneous, and when partially cooled is smooth and plastic and may be readily impregnated with the tungsten powder by simply rubbin the two together 1n a chemists mortar. T e powder goes in very readily and the binder can be heated relatively hot without danger that the components will separate,in otherv words that the alloy will break upin'to its component elements. Tungsten may be added to theextent of 30 to per cent. by weight of the final mixture. I call the product a mixture because I do not at present believe that the tungsten alloys or combines in any way with the material of the binder. The mixture is ductile and pliable and can be readily rolled or worked by any of the well known metal workin processes.

To 0 tain wires, plates, rods or other forms suitable for the construction of lamp filaments'or other apparatus, I squirt or extrude the plastic mixture above mentioned through a die, for example, a diamond die, at the temperature at which the mixture is soft and workable,'say 100 to 150 degrees C. The material comes out as a smooth homogeneous wire, not only ductile and pliable,

ut also so tough that it can be given a sharp twist and then be straightened out without danger of rupture. It may be squirted in sizes varying from large rods or plates down to wires havmg a diameter of 1 mill or even less, and can be readily rolled or worked by anyof the well known metal working processes. The ductile wire is next cutto length and bent into loops having the shape of lamp filaments. A bundle of these loops is placed on a piece of wire gauze mounted in a lass tube. The tube is then evacuated and heatedby a Bunsen burner to drive 5 Enough of the binder stays behind to hold the tungsten together and render the filaments strong enough for subsequent hanmg. The baked filament loops above described are next suspended in treating bottles and heated with current to drive out the remainder of the binder. Each loop can be suspended in a treating bottle between metal clamps. The treating bottle should be evacuated with a good mechanical pump and should be maintained dry by the use of an absorbing agent, such as phosphorous pentoxid. I prefer to have this drying agent in close proximity to the filament, as n a 2 small dish placed immediately below the filament during treatment.

The treatment of the filament loop is carried out by passin r the loop until the binder is driven out and then a higher current for fifteen to thirty seconds or even for a minute. The high current sinters the residue and shrinks the loop into'a compact homogeneous wire havinga bright metallic surface. The sintered loop 0 is strong enough for commercial use in in candescent lamps and can be operated in lamps at a very high efficiency.

As a modification of the :processes above described I may reduce the lead content to 2% parts and add to the metallic binder 2% parts bismuth. This bismuth comes out of the filamentary conductors during the heat treatment in much the same way that the cadmium and other components come out.

40 It probably comes out later, however, and

therefore is effective in strengthening the sintered and shrunk.

a low current through.

filaments durin that interval of time when they are free from cadmium but not yet Such a binding ma terial-that is one containing cadmium, lead, bismuth and mercurycomes within the terms of the annexed claims which specify that the binder is an alloy containing cadmium, lead, and mercury or is an amalgam containing cadmium and lead.

What I claim as new and desire to secure by Letters Patent of the United States, is

1. A composition of matter consisting of refractory metal powder bound togethenby an amalgam containing cadmium and lead. 2. A composition of matter consisting of refractory metal powder bound together by an alloy containing cadmium, lead and mercury. s 3. A composition of matter consisting of powdered tungsten bound together b an amalgam containing cadmium and lea 4. A composition of matter comprising powdered tungsten bound together by an alloy containing cadmium, lead and mercury.

5. A conductive pliant wire consisting of WILLIAM J). COOLIDGE.

Witnesses:

BENJAMIN B. HULL, HELEN Onroan. 

